But what's really interesting is the tools they're using to do so. When I looked over people's shoulders, I saw terminals and a web browser. They're not using Macs because their development tools require them, they're using Macs because of what else they get - an aesthetically pleasing OS, iTunes and what's easily the best trackpad hardware/driver combination on the market. These are people who work on the same laptop that they use at home. They'll use it when they're commuting, either for playing videos or for getting a head start so they can leave early. They use an Apple because they don't want to use different hardware for work and pleasure.

Apple's laptops are still the best PCs money can buy at the moment (despite their horribly outdated displays). It's no wonder Linux developers, too, favour them.

Indeed. I own a Dell Sputnik to develop, but for an iOS app development I need a Mac. My preferred SW stack for app development is Apache Cordova (a nice cross platform app envrionment) with Ripple as iOS simulator, but in order to release the software and to test it on a real iOS device, I have bought the cheapest Mac Mini available.
Although Apple has great HW and OSX is a nice environment, some Apple SW are not really that great. iTunes is just bloatware, the Finder was 10 year ago a nice file manager, but now it is outdated. Only Keynote is a decent component of the Apple iWork, Pages is only so and so, and Numbers is only a gimmick with poor functionality.